In this study, two experiments were conducted to investigate effects of script types on reading of Japanese sentences and determinants used in deciding fixation positions in reading of the sentences. In the experiments, the script types were varied as experimental variables, and reading times and eye movements were recorded. The results of the experiments revealed the followings.1. Spaced hiragana sentences were read faster with fewer fixations and shorter gaze durations than unspaced sentences. In addition, first fixation positions in words of the spaced sentences were closer to the optimal viewing position than those of the unspaced sentences. These results suggested that spaces between words made syntactic parsing easier and were used as cues in deciding the first fixation positions in words in reading of hiragana sentences.2. In reading of kanji-kana mixed sentences, effects of spacing were not found on the reading time and the measures of eye movements. Unspaced kanji-kana mixed sentences were read faster with fewer fixations and shorter gaze durations than unspaced hiragana sentences. In addition, kanji characters and/or hiragana characters next to kanji characters were fixated more frequently than hiragana characters next to hiragana characters in reading of kanji-kana mixed sentences. These results suggested that kanji characters made syntactic parsing easier and were used as cues in guiding the eye in reading of kanji-kana mixed sentences.3. First fixation positions in words of hiragana sentences and of kanji-kana mixed sentences were closer to the beginnings of the words when the locations of prior fixations lay further to the left of the words. These and above mentioned results suggested that the fixation positions in reading of Japanese sentences were determined depending not only on low-level visual processes that detected spaces between words and kanji characters but also on the locations of the prior fixations.